A joint meeting with the Chemistry and Geology Sections was held in order to discuss the question of Soil Surveys. At this meeting the following papers were read:—

Mr. Rigg illustrated his lecture by means of soil survey maps of Nelson province and lantern slides.

An interesting paper by Mr. H. T. Farrar, of the Agricultural Department, was also read, and an animated discussion followed. Some of the speakers expressed doubts as to the value of soil surveys and soil analyses, and contended that experimental work was the best way of deciding what the soil was best fitted for and how best to treat it.

Professor Easterfield (director of Cawthron Institute) maintained, however, the great value of soil survey and soil analysis work. The assistance Mr. Rigg had been able to give to farmers and others as the result of that work fully justified it, he stated; it had the effect of checking land, speculation.

One of the most interesting meetings of the Science Congress from the public point of view was a combined one of the biology and agricultural sections to discuss the problem of blackberry control. Dr. R. J. Tillyard presided, and the discussion was opened by Mr. A. H. Cockayne. Mr. Cockayne disclaimed any great knowledge of the subject. Popularly, he said, for some reason he did not quite understand, the blackberry was considered to be the most serious weed menace in the Dominion. It was not clear why the blackberry should be so viewed when the matter was considered in proper perspective. The blackberry was not causing a great diminution of the production; not nearly as much, for instance, as the common bracken. The reason why is was so seriously viewed was the danger that it might become dominant over intensely cultivated land. He believed he was correct in saying that the blackberry had not overran any land capable of carrying two sheep to the acre in winter. With many weeds, proper management of stocking tended to reduce their spread. This would also hold good of blackberry if it were not for the fact that blackberry tended to reduce the stock on the land. Frequently areas that were only comparatively badly infested were sparsely stocked because of the trouble blackberry caused with sheep, for instance. In the majority of instances, the cleaning up of blackberry was confined to those areas that could be ploughed. There was no reason why blackberry land that was ploughable should not be made good grass land by good farm management. The majority of the unploughable land now occupied by blackberry did not come under the heading of first-class land. There was, however, an exception in the area from Napier to Wairoa, where until lately the farmers had done nothing to prevent the spread of blackberry or to comply with the provisions of the Noxious Weeds Act. Recently the farmers there had come to the conclusion that they were

being seriously menaced and had applied to the Government to free them from the menace without cost to themselves. At present there was a good deal being done in cutting and spraying, and by the use of goats to control the pest. Blackberry had distinct ecological relationships as far as distribution was concerned, and he would like to see this carefully studied. There were large areas in New Zealand in which it would be impossible for the blackberry to spread, but, on the other hand, there were large areas where it could become a menace. A bonus of £10,000 had been offered for a method of eradicating the blackberry. He himself had drawn up the conditions and could say that any man who complied with them would have earned the £10,000. The basis was that the method must not be more expensive than the cost of twice cutting down the blackberry. They had a graduate of Otago University specifically engaged on the study of the blackberry and its relation to soil, climate, and other conditions. The present position as far as spraying was concerned was not so satisfactory, save that the sprays that were most toxic were expensive. They usually included arsenic, and that was a danger to stock where the area was not safely fenced off. The method that probably was giving the best results at the present time was the use of goats.

In the use of goats there was a certain amount of what he might call farm ritual to be observed. The main objection to goats was they were the greatest jumpers in the world, and the fencing necessary to keep them in would bankrupt any wool king. Dr. Tillyard said he would deal with the question simply from the point of view of control by natural enemies. His information was that the menace was serious, and was increasing, and he knew of a number who had thrown up their farms on account of blackberry. Till recently there was only one case of the control of a weed by its natural enemies. This was the case of the lantasia in Hawaii where the actual seeding of the plant had been stopped by the introduction of insects. In Australia there was a wonderful illustration of what could be done with the prickly pear, which now covered an area as large as Tasmania, and was said to be increasing by a million acres a year. A company had been floated with a large capital for clearing land by means of a heavy gas, but the company had never paid. Many other methods had been suggested, until the only thing left was to attempt to control it by the natural enemy. The insects already liberated were now doing magnificent work, and, in the opinion of the officers concerned, it was only a matter of time when the whole of the pest would be cleared out by these insects. As a biologist he held that the position here was serious enough to warrant the attempt to control the blackberry by insects. If the authorities in Australia had been guided by the opinions of leading biologists and entomologists they would never have taken the risk of introducing the insects. They felt that the position was so desperate that a desperate remedy must be tried. A group of thirty insects was gathered from North and South America, and these were all carefully tested on as many as seventy different economic plants as well as on prickly pear, before they were liberated. Only those were liberated that attacked nothing else than the prickly pear. He thought himself that the chances of control of blackberry in this way were about 50—50, but he did not want that to remain an opinion, but to have it thoroughly tested. His first proposition was that no insect except one that fed only on the genus Rubus should be allowed to enter New Zealand. He was against taking any risk for other plants. He thought the starvation test should be applied to the insects under observation at different stages of their development, both in the country of their origin and in New Zealand. He was not asking permits to liberate insects, but to bring them in under strict quarantine conditions. It was essential that they should have large insectaria with room to grow quantities of blackberry under natural conditions. Every part of the blackberry from the root up was attacked in some part of the world or other by insects. There were two insects which offered tremendous possibilities, by attacking the tips of the shoots and the fruiting head. There would be grave danger of it attacking raspberry. There was another insect found in Belguim which did grave damage to the stems. There were a great number of leaf feeders that might combine with the other insects he had mentioned in attacking the blackberry. He was to fight